The fresh packed quality attributes of fresh fruits and vegetables must be maintained as much as possible for as long as possible to ensure consumer acceptability. Quality deterioration of horticultural produce comes about through water loss for the tissue. Methods of inhibiting the deteriorative enzyme reactions, and the growth of yeasts, molds and bacteria involve the reduction of the produce temperature to between 1.degree. to 12.degree. C., and the creation of low O.sub.2 /high CO.sub.2 modified atmospheres around the produce. Water in fruits and vegetables can be lost readily under low relative humidity conditions with the consequence of skin wrinkling, wilting and reduction in crispness. The rate of water loss from produce can be restricted by storing the produce in closed package systems consisting of walls with low moisture permeability.
GB-A-2 096 052, Lin Pac Containers Limited, discloses corrugated board which is designed principally for water resistance. There is no disclosure in the specification that is directed to regulating gas transmission rates through the board. However, the construction of the corrugated board is relevant. The corrugated board is constructed of two outer facer layers which are laminates comprising a first layer and a second layer, with a plastic intermediate layer. The centre of the board is corrugated kraft fluting. The first outermost layer can be greaseproof paper. The intermediate plastics layer can be polyethylene.
GB-1-1 592 880, Unilever Limited, discloses a moisture resistant composite material comprising cardboard, paperboard, or similar foldable board material. The objective is to provide a moisture resistant composite material useful for constructing cartons for packaging moisture sensitive materials. The composite material comprises a first layer of board material to form a facing layer, a second layer of kraft paper which is corrugated and attached to the first layer and a third layer of board material which is attached to the second layer. The third layer can be laminate of two sheets of board material (kraft) with a thermoplastic moisture barrier therebetween. At line 40 of page 1, it is stated that the thermoplastic moisture barrier may be polyethylene. There is no mention in this patent of controlling oxygen and carbon dioxide transmission rates through the walls of the moisture resistant composite material.
EP-A-0 332 742, Nekoosa Packaging Corporation, discloses a corrugated paperboard construction which includes a layer of plastic film of approximately 1-3 ml thickness. The thermoplastic co-extruded polymer film can be high density polyethylene, polypropylene, PET. The construction can be used in a single wall or multi-wall corrugated paperboard container having good moisture vapour transmission resistance. The containers are suitable for packaging food and chemical products. Again, this patent discloses paperboard constructions which include a layer of plastic film. However, there does not appear to be any disclosure of gas transmission rates, the principal objective being to control moisture vapour transmission.
GB-A-1 296 040, Owens-Illinois, Inc., discloses a paperboard container having built-in water resistance. There is no disclosure of gas transmission rates. However, FIG. 2 illustrates a paperboard construction which comprises an outer liner board 44, a corrugated kraft fluting 42, and an inner linear board 34, which is a laminate of a kraft liner board 26, an intermediate layer of thermoplastic film 22, and an inner layer of bag stock 20. As with the other patents discussed, this patent also discloses a paperboard construction which includes a combination of kraft paper, corrugated paper, and plastic film.